android - onCreate being called on Activity A in up navigation -

so have activity , activity b. want activity able navigate activity b press of button. works, when use navigation(the home button in action bar) navigate activity a, oncreate() called again , old information user typed in lost.

i've seen: oncreate called if navigating intent, used fragments, , i'm hoping not have redesign entire app use fragments. there way can stop oncreate() being called every time activity becomes active again?

this behavior totally fine , wanted. system might decide stop activities in background free memory. same thing happens, when e.g. rotating device.

normally save instance state (like entered text , stuff) bundle , fetch these values bundle when activity recreated.

here standard code use:

private edittext msomeuserinput; private int msomeexamplefield;  @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);      // todo inflate layout , stuff     msomeuserinput = (edittext) findviewbyid(r.id.some_view_id);      if (savedinstancestate == null) {         // todo instanciate default values         msomeexamplefield = 42;     } else {         // todo read instance state savedinstancestate         // , set values views , private fields         msomeuserinput.settext(savedinstancestate.getstring("msomeuserinput"));         msomeexamplefield = savedinstancestate.getint("msomeexamplefield");     } }  @override protected void onsaveinstancestate(bundle outstate) {     super.onsaveinstancestate(outstate);     // todo save instance outstate     outstate.putstring("msomeuserinput", msomeuserinput.gettext().tostring());     outstate.putint("msomeexamplefield", msomeexamplefield); }